1. Field of the Invention
The present invention relates generally to manufacturing optical fibers, and particularly to techniques for remediation of optical fiber manufacturing effluent material.
2. Technical Background
Optical fibers have acquired an increasingly important role in the field of communications, frequently replacing existing copper wires. This trend has had a significant impact in the local area networks (i.e., for fiber-to-home uses), which have seen a vast increase in the usage of optical fibers. Further increases in the use of optical fibers in local loop telephone and cable TV service are expected, as local fiber networks are established to deliver ever greater volumes of information in the form of data, audio, and video signals to residential and commercial users. In addition, use of optical fibers in home and commercial business environments for internal data, voice, and video communications has begun and is expected to increase.
As use of optical fiber increases so does the demand for optical fibers, which are able to offer improved or new properties as compared to fibers already in use. Efforts to produce such fibers have included producing a fiber doped with a halogen, e.g., fluorine, at specific radial locations in a silica glass matrix to depress the index of refraction relative to the index of refraction of pure silica to achieve desired optical properties. Such efforts result in a halogen containing effluent.
However, existing environmental laws regulate point source emissions of at least SiO2 and some halogen containing compounds, e.g., fluorine containing compounds. Typical point source emissions include the regulation of air emissions, water emissions, or solid emissions. With respect to point source emissions, the allowable water point source emissions are very limiting, the regulated water point source emission may be as low as parts-per-million of a halogen (e.g., fluorine). Thus, systems that do not require water point source emissions, preferably systems that do not require water or air point source emissions, are desirable in a manufacturing environment.
Unfortunately, existing processes for abatement of a halogen containing effluent typically include a pretreatment or post treatment scrubbing of a hydrogen-halogen containing gas (e.g. HF) with an aqueous scrubber. These processes all lead to the formation of a halogen containing water point source emission. Also, subsequent processing of the halogen containing water is a timely and capital intensive project. Therefore, there is a need for a new method to abate halogen effluents from a glass manufacturing facility that does not include an aqueous or gaseous halogen point source emission.
One aspect of the invention is a method of treating a substantially gaseous halo-containing compound of an effluent of a glass manufacturing facility. A step of the inventive method includes oxidizing the halo-containing compound to form a hydrogen and halo-containing compound. A second step of the method comprises adsorbing a halogen of the hydrogen and halo-containing compound on a surface.
In another aspect, the present invention includes a system for treating a substantially gaseous halo-containing compound of an effluent of a glass manufacturing facility. The system includes at least one glass manufacturing apparatus which the operation of the apparatus, in glass manufacturing, generates an effluent which comprises a substantially gaseous halo-containing compound. The system further includes an oxidizer in fluid communication to receive the halo-containing compound and oxidizes the compound to transform the halo-containing compound into a hydrogen and halo-containing compound. The system also includes a scrubber for receiving the hydrogen and halo-containing compound and adsorbing the halogen from the hydrogen and halo-containing compound.
An advantage of the invention is that it is a new process for abating halogen containing compounds (e.g., CF4 and HF) contained in the effluent of a fluoride doping process in the manufacturing of a glass product. Another advantage of the invention is that the method of the invention will not result in the production of an aqueous or airborne halogen point source emission. A further advantage of the invention is that invention is a substantially water free process. An additional advantage of the inventive process is that the halogen is converted into an inert dry-waste by-product.
Furthermore, advantages of the invention include the ability to construct an abatement system to include components and redundancies to enable rapid response to out of service conditions which minimize loss of ware and capability to start up the system in a short period of time. Minimize loss of ware is used above to mean at least a production run or runs that are in process when a component of the abatement system becomes inoperable are not required to be scrapped. A short period of time is used herein to mean that a back-up piece of equipment can be on-line and operating as part of the system in less than about 60 minutes, preferably less than about 45 minutes, and more preferably about 30 minutes or less. Also, the abatement system is designed to operate continuously while the sources of the halogen to be abated may be operated as a batch process.
Other advantages of the inventive process include: (1) the ability to process CF4 and HF without an aqueous pretreatment; (2) the effluent of the inventive process is substantially free of SiO2 particulate; (3) the remediation process can result in an inert solid waste by-product; (4) the entire remediation system may be operated under a vacuum to prevent exposure to personnel of non-benign compounds (e.g., HF) and equipment damage; (5) an efficient abatement system to remove high volumes of CF4 and HF from the optical manufacturing process; (6) the inventive system also has the capabilities to provide particulate control in the effluent of the glass manufacturing facility; (7) a single oxidizer may used to oxidize the effluent from more than one furnace; and (8) the inventive process may be used to abate chlorinated, fluorinated, iodinated, or brominated derivatives of carbon and hydrocarbon materials.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operations of the invention.